Outlook Slow and Unresponsive wiht MAPI over HTTP to Exchange 2016 Server

In our case the versions in question were found to be:

Outlook 2013 connecting to Exchange 2016 with MAPI over HTTP enabled.

Reported Problems

The user reported that outlook was slow to open email, and unresponsive with searching in outlook.

The CTRL right click on the Outlook connection icon (bottom right) showed the connection was made with HTTP

The Problem

It is reported that MAPI over HTTP which is a newer connection method of laterExchange servers and potential better and more reliable for devices connecting has some unreliabilities in some instances with earlier version of Outlook.

Our testing shows that later outlook versions and the Mac versions of outlook have no troubles at all.

The Solution

IN Exchange 2016 it is possible to disable MAPI for a users mailbox. The issue this may have is that they could have other more recent devices such as phones and tablets that are enjoying the advantages of MAPI over HTTP.  So rather than turning off MAPI for all their devices at the exchange server end. It is preferable to disable the connection on that users computer only.

This can be easily done using regedit.

Disabling MAPI over HTTP with Regedit

1. Log on to the proxy client where you installed the agent.

   Use the credentials for the Windows account that you defined in the agent properties.

2. In Windows on the client computer, click Start, and then type regedit in the Search programs and files box.
3. Press Enter.

   The Registry Editor appears.

4. Expand HKEY_CURRENT_USER > Software > Microsoft > Exchange.
5. Right-click Exchange, and then click New > DWORD.

   A new DWORD entry appears in the right pane.

6. Right-click the new DWORD entry, and then click Rename.
7. Type MapiHttpDisabled.
8. Right-click the MapiHttpDisabled entry, and then click Modify.

   The Edit DWORD Value dialog box appears.

9. In the Value box, type 00000001, and then click OK.
10. Close the Registry Editor.
11. Verify that the protocol has been changed to RPC over HTTP.
    1. Restart Microsoft Outlook.
    2. Press Ctrl and right-click the Microsoft Outlook icon in the notification area at the far right of the task bar.
    3. Click Connection Status.

       The Microsoft Exchange Connection Status dialog box appears.

    4. Verify that the value in the Protocol column is RPC/HTTP.
    5. If the value is HTTP, delete the Microsoft Outlook profile, and then recreate it.

Disable MAPI over HTTP using .reg file.

1. Download this file: MAPIoverhttp_disable.zip

2. Unzip the file

3. Double open the MAPIoverhttp_disable.reg file and it will add the above change for your.

Disabling MAPI over HTTP using Command Prompt.

1. Click Start RUN

2. Type CMD then hit ENTER.

3. Type or paste: REG.exe Add HKCU\Software\Microsoft\Exchange /V MapiHttpDisabled /T  REG_DWORD /D 0x1 /F
(Note that the above is one line that may wrap)

Disabling MAPI over HTTP using PowerShaell

We can retrieve the current configuration using the first two commands, whilst the third one disables MAPI/HTTP and the final command enables MAPI/HTTP:
Get-Item HKCU:\Software\Microsoft\Exchange
Get-ItemProperty -Path HKCU:\Software\Microsoft\Exchange -Name MapiHttpDisabled | select MapiHttpDisabled | Ft –AutoSize
New-ItemProperty -Path HKCU:\Software\Microsoft\Exchange -Name MapiHttpDisabled -PropertyType DWORD -Value “0x1” –Force
New-ItemProperty -Path HKCU:\Software\Microsoft\Exchange -Name MapiHttpDisabled -PropertyType DWORD -Value “0x0” –Force
(Note that the above are all one line that may wrap)

Testing When MAPI/HTTP Disabled

For reference, Outlook 2010 connection information is show.  Note that MAPI/HTTP is being used:

After disabling MAPI/HTTP using one of the above methods, reg.exe or PowerShell, we can then look to see how Outlook is connecting.  Note that you may have to wait for Outlook to perform an Autodiscover request and automatically update itself, or alternatively run a profile repair to force a full Autodiscover.  Deleting the Outlook profile would also force the change, but that is not recommend in production unless it is the last resort.  Deleting Outlook profiles causes OAB downloads, OST downloads, possibly adding PST files back into the profile and may also impact mobile devices.

In the below screenshot we can se that the client is now kicking it old skool.  The protocol type has changed, and there is now a proxy server specified. This was taken after restarting Outlook.

Enabling Via Command Prompt

To allow MAPI/HTTP remove  the MapiHttpDisabled DWORD, or set it to a value of 0 as shown below:

REG.exe Add HKCU\Software\Microsoft\Exchange /V MapiHttpDisabled /T  REG_DWORD /D 0x0 /F

(Note that the above is one line that may wrap)